Core member for casting printing plates



Sept. 4, 1928. 1,683,356

I. E. HURLBUT CORE MEMBER FOR CASTING PRINTING PLATES Filed Dec. 1925 fag 0 11 v; 1, is f -A is the bottom or the casting: box.

Patented Sept. 4, 1928.

U N ET'E. SLT'FES IRA E. HURLBUT, OF PRAIRIE DU (SH-TEN, WISCONSIN.

CORE MEMBER FOR CASTING PRINTING PEATES".

Application filed December 7, 1925, Serial Ii'o, 73,636.

The purpose of this invention is to provide an improved means tor casting printing plates such as stereotype plates. and the like in, which: the printing face is formed upon a papier-maich matrix, said means being an improved, construction of the cores which produce the recessesin the back of the stereotype plate. The invention consists in the elements and features, of construction shown and described, and the method of its use, allasset forth in the claims.

7 In the drawings.:-

Figure. 1 is. aback or top. plan View of a core embodying and adapted for use according to my invention, showing in dotted outline a, minimum printing plate in the casting of which this core member may be used.

Figure 2 is a section at the line 22- on Figure 1, showing als the pa-pier-mach matrix with which the core -CO-PGYZth6S in casting, and also showing the bottom plate of; the casting box and the encompassing bars which form the boundary wall of the cavity in whichthe casting is to be formed.

Figure 3 is a section similar to Figure 2, showing the cover of the casting be}; appliedand forced down upon, the core liorlclosing the cavity in which the. metal is. to flow for forming the printing plate.

Figure 4 is a perspective view of a casting box with the cover swung up and having in position on the bottom, the-mold, sidebars and a plurality of core members embodying this invention.

In the structure shown in the drawings, B is the cover. C indicates the bars formingthe encompassing wal of the mold cavity. in which the r inti1 ig: face is to be cast. D is the matrix lodged on the bottom plate. 1211c corc whjchembodies the present invention is indicated as to its entirety by reference letter E. It consists of ahard metal block having a cavity in the upper side, rendering it dished in the form Its exterior contour being suitable for forming the customary core cavity in the back of the printing plate. It is characterized for the purpose of the present invention by a plurality of conepointed downwardly projecting pins, and 11, 11. These pins are mounted in the bot tom web of the core body, E, and project through the same for a distance a little more than the length of their tapered portion or cone points indicated at 12. The core body, E, is formed with an upwardly projecting intermediate its ends and sides shown at 13, said boss being slightly less in height than the encompassing wall, 14, of the core cavity; and the pin, 10, is screwed through this boss andis thereby adjustable with re spect to the extentot the protrusion of its cone point from; the bot-tomof the core.. The

other pins, 11 11, ar'e mounted in the bottom oi the core, loosely to the extent that they are free to. slide-in their seats and they are each formed with a stop head, 11-, at the upper end for limiting their protrusion through the bottom oi the; core, and they. are held yieldingly protruded to this limit by flat springs, 15, 15, secured at one end near the boss, 13, by screws,1:6, 1;t3, the other free end resting uponheads of the pins, 11,. 11,. as seen clearly in Figures 2 and 3. The height of the corebody, E, is siichthat, its height added tothe protrusion of: the pins, 11, 11, when they are protruded to the limit determined by their heads, 11*, slightly exceeds the height. of the encompassing side bars which are the-conventional type height and the screw, 10, will be adjusted in: the core body to make the total height, including its protrusion when thns adjusted, conform to type height, with a; slight allowance for p08.- sib-le penetration of the matnix by the points oi said pins.

The method of using this core is as follows: The matrix havingbeen placed upon the bottom oli the core box, and the encompassing side bars being placed in position upon the matrix for pressing it onto the bottom-of the box, the core is placed inposition above the matrix, the pins, 10 and; 11, being. stepped: upon tihe matrix as may be seen in Figures 2- and 3. stood the matrix is liable'to; be sprung-or bowed slightly out of true plane at pontions of its area as is represented at 17 in Figure 2, and the purpose of the pins stepped upon it at plurality of positions indicated by the three pins shown in the drawing, (it being understood that the number is not limited to three) is to insure that the matrixis held pressed flat upon the bottom plate of the mold; and this result is ellected by mounting all but one of the pins mounted yieldingly as shown, and providing the springs, 15, of sullicient stiffness to force the matrix into fiat. form, overcoming the resilient resistance of its sprung or bowed portions. WVhen in this position, the margin of the core projects above the plane of the upper edge of the side As is well underbars, C, that is, projects above type height from the bottom of the casting box. The cover is now closed down upon the side bars and made fast by means provided for that purpose, thereby forcing the core body down, bringing its upper edge into the plane of the upper edge of the side bars, the pins, 11, 11, yielding back to whatever extent is necessary, and thereby applying theyieldingpressure to the matrix at the points at which the points of the pins rest thereon. It may chance that the points of the pins rest upon upraised portions of the matrix which may therefore be pierced by pin points; but these upraised portions, it will be understood, correspond to depressions in the printing face from which no imprint is to be produced, so that the perforations of the matrix at these points by pins is uninjurious and negligible.

It is to be understood that the springs, 15, may be of sufficient stiffness so as to react through the pins, 11, against the casting formed in the casting box for normally causing ejection of the core body, E, from the finished casting when the cover, B, is removed. However, there may be instances when the casting will adhere to the pins, 11, so tightly as to overcome the tension of the springs, 15, and by turning slightly the threaded adjustable pin, 10, by means of a screw driver or like tool, the core body may be easily dislodged and ejected from the casting by said springs.

I claim l. A core member for casting printing plates having pressure points mounted for protruding from its inner face for stepping on the matrix, said core member comprising a core body less than type hei ht, the pressure points being afforded by pins set through the core body for protruding from the face, means for yieldingly holding the pins protruded, and means for limiting the protruded length, said protruded length being more than the deficiency in type hei ht of the core body; whereby said pressure points stepped upon the matrix uphold the core body to a height in excess of type height.

2. In the construction defined in claim 1, he range of yielding of the pins being lightly more than the normal protrusion of .id pins through the core body plus the eight that said core body extends in excess f type height.

A core member for casting printing plates, having pressure points mounted therein protruding through the inner taco, and spring bars by which said pressure points are yieldingly held thrust out through said face.

4. The construction defined in claim I havone of tie pressure points mounted in the core body adjustably as to the degree of its protrusion from-the face, and a plurality of the other points mounted for protruding yieldingly farther than said adjustable point.

5. In the construction defined in claim 1, the pressure points being afforded by pins fitted slidably in holes in the face web of the core body, having their protruding ends comrpo nted for stepping on the matrix, and spring means for holding them yieldingly thrust out, said pins having means at their inner ends for limiting the protrusion of their pointed ends,

(5. In combination with a casting box and a cover therefor, a matrix disposed in the bottom of said box, a core body disposed in spaced relation on said matrix, and means carried by said core body for ejecting the same from the casting formed in said casting box, when the cover is removed therefrom.

7. In combination with a casting box and a cover therefor, a matrix disposed in the bottom of said box, a core body disposed in spaced relation on said matrix, and yielding n1 vans carried by the core body and removable therewith for normally projecting a portion of said core body above said casting box when the cover is removed and adapted to permit said core body to be forced within the casting box when said cover is applied thereto.

In testimony whereof, I have hereunto set my hand at Chicago, Illinois, this second day of December, 1925.

IRA E. HURLBUT. 

